(1) Field of the Invention
The present invention relates to a control valve for use by being attached to outlets of, for instance, a high-pressure gas container. Particularly, the present invention relates to a control valve and a diaphragm therefor for use in a gas container containing a corrosive gas.
(2) Related Art
A container for enclosing a gas, such as a gas cylinder for propane, has a gas control valve at the outlet thereof. By opening or closing the control valve, the gas enclosed in the container is discharged or sealed hermetically.
Such a conventional control valve is constituted of a valve body, a diaphragm, a fastening member to fix the diaphragm; a valve controlling member, and an operating device for the valve controlling member. Inside of the valve body, are formed a valve chamber wherein a valve member is contained and a valve seat therefor is formed, a gas inlet which has an opening in the center of a valve seat to be connected to the valve chamber, a valve seat in the center of which the opening of the gas inlet is provided, a gas outlet, and a cylindrical portion whose inside space is connected to the valve chamber. The diaphragm is arranged between said inside space of the cylindrical portion and the valve chamber, and the fastening member is threaded in the inside space of the cylindrical portion to fix the diaphragm against the valve body. The valve controlling member is inserted through the center of the fastening member to urge the diaphragm against the gas inlet provided in the valve seat.
By moving the valve controlling member back and forth with the operating device, the diaphragm is closed or opened to the valve seat to enclose or discharge the gas in or from the container.
In case, however, that a strong corrosive gas is enclosed in the container, the diaphragm is easily damaged and the durability thereof decreases due to the fact that the diaphragm is made to contact the gas. Even if a material having a high resistance to corrosion is used for the diaphragm, when the gas flows from the inlet to the valve chamber, the part of the diaphragm being in contact to the valve seat is directly subjected to the corrosive gas, so that this part is particularly apt to be corrosive.
Further, the part of the diaphragm is always made to contact the corrosive gas even when the valve is closed. Therefore, corrosion is caused there more frequently. When corrosion is caused partially in this manner, a stress is concentrated there so that cracking would be easily generated therefrom.
The present invention has its purpose to provide a control valve having a high durability and a diaphragm therefor, which are suitably used in a corrosive gas flow path.
A control valve according to the first invention comprises a gas current in path through which a gas flows in; a gas current out path through which the gas coming from said current in path goes out;
a valve chamber being provided between said current in path and said current out path,
a valve body comprising a cylindrical portion having an inside space which is connected to said valve chamber;
a valve seat being provided in said valve chamber where an outlet of said gas current in path is open;
a diaphragm separating said valve chamber from said inside airspace of said cylindrical portion;
a clamp surface being provided in said valve body;
a clamping member being urged against said clamp surface to hold said diaphragm between said clamp surface and the member itself;
an urging member having a resistance to corrosion and being fixed to said diaphragm;
a valve control member being contained in a center of said clamping member in a movable condition in advance or retreat directions and urging said urging member of the diaphragm against said valve seat; and
an operating means for controlling the movement of the valve control member in advance or retreat directions.
The present invention has another aspect that the urging member is made of ceramic.
The present invention has still another aspect that said diaphragm has a flexible portion by which a flexure thereof is absorbed.
The present invention has its second purpose to provide a diaphragm for use in a control valve used in a corrosive gas flow path, which comprises a thin plate member having a flexibility; and an urging member made of ceramic being fixed to the center portion of said thin plate member.
The second invention has another aspect that said diaphragm for use in a control valve has a concave flexible portion which is formed in a peripheral portion of an area where said urging member is fixed.
The second invention has another aspect that said diaphragm for use in a control valve comprises an inserting member made of metal being inserted between said thin plate member and said urging member.
The second invention has still another aspect that said urging member has a tapered surface.